Each Layer

So in total, I ended up with the following amounts of splats for each layer of the nebula.  (NOTE: PDF2 = quadratic, PDF3 = cubic)

LOW
Opaque:                           402,166
Transparent:                  3,715,018
Trans w/ PDF2:              1,295,449
Trans w/ PDF3:              980,540

TOP
Opaque:                           778,473
Transparent:                  7,812,353
Trans w/ PDF2:              2,600,015
Trans w/ PDF3:              1,950,661

Here's each layer from the render code:

Low Opaque

Low Transparent (PDF2)

Top Opaque

Top Transparent (PDF2)